Microsporidia are ubiquitous parasites that can infect insects, fish, and mammals. Recently, microsporidia have been demonstrated to infect humans. These organisms cause ophthalmic and gastrointestinal infections, primarily in patients with AIDS. Several genera of human pathogens have been cultivated in cell culture. However, there are presently no data regarding the ability of the human pathogens Encephalitozoon intestinalis and Encephalitozoon hellem to survive under various environmental conditions. Also, there are no reports regarding the effects of disinfectants on spores of these two species. The survival of microsporidial spores after exposure to disinfectants (e.g., chlorine, alcohol, and quaternary ammonium compounds) and environmental conditions (e.g., elevated temperature and desiccation) will be studied. Cultivation of microsporidia in the shell vial system using various cell lines has been investigated, and microsporidia appear to replicate in both fibroblast and epithelial cell lines. Staining methods are being evaluated to detect microsporidial inclusions in infected cell culture after exposure to disinfectants and environmental conditions. In an effort to replace staining of infected cell cultures, a method for quantitation of microsporidial DNA is under evaluation for its ability to detect microsporidial growth in cell culture.